The present embodiments relate generally to medical devises, and more particularly, to branch vessel prostheses that may be used with a main vessel prosthesis.
The functional vessels of human and animal bodies, such as blood vessels and ducts, occasionally weaken or even rupture. For example, the aortic wall can weaken, resulting in an aneurysm. Upon further exposure to hemodynamic forces, such an aneurysm can rupture. In Western European and Australian men who are between 60 and 75 years of age, aortic aneurysms greater than 29 mm in diameter are found in 6.9% of the population, and those greater than 40 mm are present in 1.8% of the population.
One surgical intervention for weakened, aneurysmal or ruptured vessels involves the use of an endoluminal prosthesis to provide some or all of the functionality of the original, healthy vessel and/or preserve any remaining vascular integrity by replacing a length of the existing vessel wall that spans the site of vessel failure. These prostheses may seal off the failed portion of the vessel. For weakened or aneurysmal vessels, even a small leak in the prosthesis may lead to the pressurization of or flow in the treated vessel, which aggravates the condition the prosthesis was intended to treat. A prosthesis of this type can, for example, treat aneurysms of the abdominal aortic, iliac, or branch vessels such as the renal arteries.
An endoluminal prosthesis can be of a unitary construction, or be comprised of multiple prosthetic modules. A modular prosthesis allows a surgeon to accommodate a wide variation in vessel morphology while reducing the necessary inventory of differently sized prostheses. For example, aortas vary in length, diameter and angulation between the renal artery region and the region of the aortic bifurcation. Prosthetic modules that fit each of these variables can be assembled to form a prosthesis, obviating the need for a custom prosthesis or large inventories of prostheses that accommodate all possible combinations of these variables. A modular system may also accommodate deployment options by allowing the proper placement of one module before the implantation of an adjoining module.
Modular systems are typically assembled in situ by overlapping the tubular ends of the prosthetic modules so that the end of one module sits partially inside the other module, preferably forming circumferential apposition through the overlap region. This attachment process is called “tromboning.” The connections between prosthetic modules are typically maintained by the friction forces at the overlap region and enhanced by the radial force exerted by the internal prosthetic module on the external prosthetic modules where the two overlap.
When an aneurysm affects a main vessel, it is important to maintain flow to the branch vessels. The celiac, superior mesenteric, left common carotid and renal arteries, for example, are branch vessels of the aorta; the hypogastric artery is a branch vessel of the common iliac artery. If these branch vessels are blocked by the main vessel prosthesis, the original blood circulation is impeded, and the patient can suffer. If, for example, the celiac artery is blocked by the main vessel prosthesis, the patient can experience abdominal pain, weight loss, nausea, bloating and loose stools associated with mesenteric ischemia. The blockage of any branch vessel is usually associated with unpleasant or even life-threatening symptoms.